A method to make specific characters or symbols noticeable on a displayed screen is blinking. In conventional monochromatic displays, characters or symbols were merely blinked. In the early days of color displays, blinking was performed by periodical switching between a specified color and a background color (normally black). However, there are some cases where it is undesirable that a specific color goes off even for a moment. Therefore, it has been proposed to blink using two colors other than black.
In U.S. Pat. No. 4,439,759, for example, a color map memory storing a plurality of color signals is provided, and two color signals are alternately read out of this memory at the time of blinking.
In conventional color blinking systems, since color video signals stored in a color map memory are used, the number of available colors is limited. When a certain color is specified for blinking, an operator watching the screen would be confused if a different color to be displayed alternately with the specified color is used somewhere else on the screen. In order to avoid this problem, normal display colors would have to be distinguished from blink colors. In that case, however, the number of normal display colors is halved.